By-product coke oven operation



April 18, 1933. s. P. MILLER 1,904,161

BY-PRODUCT COKE OVEN OPERATION Filed l111111 18, 1929 s sheets-sheet 1 INVENTOR BY 7m' ML fw ATTORNEYS yApril 18 1933 s. P. MILLER 1,904,161

BY-PRODUCT COKE OVEN OPERATION Filed April 18,v 1929 5 Sheets-Shea?l 2 rNvENToR f BY MMI/fw ATTORN EYS April 1s, 192.3.l

lFiled April 18, 1 929 S. P. MILLER BY-PRODUCT COKE OVENl OPERATION 5 Sheets-Shet v 3 ATTORNEYS S. P. MILLER BY-PRODUCT COKE OVEN'OPERATION April 18, 1933.

Filed April 18, 1929 5 Sheets-Sheet 4 INVENTOR A v BY 7M' NRJ ATTQRN EYS April 18, 1933. s. P. MILLER BY-PRODUCT COKE OVENOPERATION Filed April 18, 1929 5 Sheets-Sheet 5 KMSSQ |NvENToR BY @L ATTORN EYS Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE STUART IARIllIIFILEIE- MILLER, 0F ENGLEWOOD, NEW JERSEY, ASSIGNOR TO THE BARRETT COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY BY-PRO-DUCT COKE Application led April 18,

This invention relates to a new and improved method ot preparing tarry oils, and more particularly tarry oils of regulated free carbon content, such as ta-rry oils which are suitable for use as. creosoting composi tions, and to apparatus for preparing the saine.

According to the present invention ho coke oven gases or gas retort gases carrying suspended heavy tar and pitch constituents are subjected to a cleaning treatment, as by electrical precipitation, or by scrubbing with pitch or tar to remove suspended tar and pitch particles from the gases, and the cleaning treatment is carried out at a suiliciently high temperature to maintain the required portion of the oils present in the gases in the form of vapors. The resulting gases are brought into direct contact with tar, preferably a light tar or tarry oil, and cooled, whereby clean oils are condensed from the gases and blend with the tar to give a tarry oil product. By cooling and recirculation of the tarry oil product, and bringing it into direct contact with the gases, together with fresh tar, a greater or lesser amount of clean oils may be separated from the gases to be blended withv the tar to give the tarry oil product. Lower boiling constituents of the tar employed for cooling the clean gases may be distilled out ofthe tar.

According to the present invention, I subject the coke oven or gas retort gases to a cleaning treatment to remove suspended heavy tar and pitch constituents therefrom and l bring the tarry oil or other tar into direct and intimate contact with thehot gases, as by washing the gases with the tar so as to condense desirable oils from the vapors carried in the gases. The cooling of the cleaned gases by the tar may raise the temperature of the tar to a point 'where low boiling constituents will-be distilled. Such clean low boiling constituents may eventuallyv be condensed from the gases together with low boiling constituents carried by the gases which are not condensed by Contact with the tar, so that in addition to a tarry oil of regulated character, a clean low boiling oil fraction may be obtained by this process.

OVEN OPERATION 1929. Serial No. 356,042.

The cleaning of the gases, according to the present invention, may be carried Vout in an electrical precipitator which may be of the type ordinarily employed for cleaning hot gases. In general the precipitator is located between the gas-collector main and the condensing system. It is advantageously located immediately adjacent the collector main so as to receive the gases at the temperature at which they leave the main and the gases leaving the precipitator will then contain substantially lall of the oils contained as vapors in the gases leaving the collector main.

The .cleaning may be carried out in a gas scrubber. The scrubber may comprise a chamber containing a. reservoir of the scrubbing medium in which a roll is so mounted that it dips to but a slight extent into the scrubbing medium. By rapidly rotating the roll, the scrubbing medium is sprayed into the gases in such a way as to effect substantial cleaning ot the gases. Diii'erent types of scrubbers may be employed, depending upon the degree to which the gases are to be cleaned.

The gases may be scrubbed with a tar or pitch of the same composition as that carried in suspension in the gases and the tar or pitch employed may be at approximately the same temperature as the gases. On scrubbing under such conditions entrained tar or pitch particles carried by the gases are removed from the gases without any substantial change in the composition of the oil vapors in the gases.

H the gases are scrubbed with a tar or pitch of composition different from that entrained in the gases lighter oils will be given up from the scrubbing medium to the gases or oils will be absorbed from the gas to the scrubbing medium, depending upon whether the scrubbing medium is rich or delicient in lighter oils as compared with the entrained tar or pitch and depending also upon the temperature and quantity of the scrubbing medium used. A tar rich in light oils, employed for scrubbing a gas at relatively high temperature will ordinarily be somewhat distilled during the scrubbing operation and will cause enrichment of the gas in lighter oil components. Likewise a pitch deficient in oil as compared with the entrained tar or pitch may remove oils romthe gases during the scrubbing operation. Under such conditions the character and amount of oil vapors in the gases may be changed and the type of pitch product recovered will be different from that obtained by scrubbing the gases with tar or pitch of the same composition as that entrained in the gas.

By bringing the tar or pitch into intimate contact with the hot gases in a chamber con taining a roll such as that above described, and rotating the roll at a high speed in the neighborhood of 900 to 1200 R. P. M., entrained impurities will be removed from the gases and if the temperature of the gases approximates the temperature at which they leave the coke ovens, the tar may be distilled to a hard pitch, as for example pitch with a melting point of 250 or 300 or even 400 F., and the oils distilled from the tar or pitch will be carried over by the gases. Where the gases have been efficiently scrubbed, substantially clean oils containing no considerable amount of tar or pitch may be obtained on cooling the resulting gases. Where the scrubbing is not so eiiicient, some entrained particles may be carried by the gases leaving the scrubber or still and in this case the gases may be further cleaned as by cleaning in an electrical precipitator.' If the gases are passed to the cleaning device from a gas collector system, such as a collector main, the temperature of the gases passing through the cleaning device can be regulated by regulating the cooling to which the gases are subjected in the gascollecting system. Ordinarily the gases in the collector main of a coke oven plant are cooled by circulation of tar and ammonia liquor through the main, or by spraying ammonia liquor into the gases passing through the main. Where such methods are employed the cooling of the gases should be regulated so as to avoid cooling to too low a temperature since it is desirable that a considerable portion of the heavier oils remain in vapor form when the gases leave the collector main and pass through the cleaning device. By reducing the extent to which the gases are cooled in the collector main the gases may be passed into the cleaning device at a. fairly high temperature, for example, 200o C. or higher. The cleaning treatment at such temperatures removes entrained pitch particles from the gases while leaving oil vapors in the gases so that if the gases were to be cooled after the cleaning operation, clean oils or relatively clean oils would be obtained containing oils of higher boiling range.

Where the hot gases are employed for distilling tars simultaneously with cleaning of the gases by the tar, and Where the distillation of the tar is carried sufficiently far to produce a high melting point pitch, for example a pitch with a melting= point in the neighborhood of 400 F., it may be desirable to irst separately condense higher boiling constituents from the gases leaving the still and to thus produce a separate high boiling resinous or greasy distillate and then to use the remaining gases for the preparation of the tarry oil product by bringing the resulting gases into direct contact with the tar, as in making creosoting composition according to this invention. Such procedure allows the collection of extremely heavy coal tar distillates and in addition permits the production of the desired creosoting composition. It particularly enables one to regulate within close limits the character of the creosoting composition.

The process of this invention may be so regulated that the tarry oil product obtained can be directly employed as a substitute for the ordinary creosoting compositions of the type known as coal tar solution. FIn special cases it may be desirable to eliminate a part or all of the lighter oils from the tarry oil produced or to add tar or to add distillate oils to this tarry oil before use as creosoting composition.

In making ordinary coal tar solutions, the greater part of the tar collected from the coke oven gases is distilled and the distillate is blended with a relatively small proportion of undistilled tar usually in the proportions of 80% of distillate to 20% of tar to make the coal tar solutions of commerce. The distillation of this large amount of tar is expensive and when distilled by the usual methods considerable decomposition of oil takes place during the distillation With resulting loss of valuable oil and corresponding increase in pitch production.

When preparing creosoting composition according to this invention, the necessity of distilling such large quantities of tar to produce distillate is obviated. The amount of tar used for condensingthe clean oils from the cleaned gases may be regulated so that the product produced, even after removing any excess of loW boiling constituents, will have a suiicieutly low content of so-called free carbon to enable it to be employed directlv for creosoting composition Without the addition of distillate thereto. If the content of tarry matter as evidenced by the content of so-called free carbon is not-suiicient in the tarry oil produced, additional tar can be blended therewith, but in any event the distillation of a large amount of tar to produce a large amount of distillate oils is made unnecessary.

The free carbon content of the tarry oil product of this invention may be controlled by regulating the proportion of tar and clean oils which are blended to form the creosoting composition or other tarry oil product.

Gases which have been subjected to a cleaning treatment which removes substantially all entrained impurities from the gases, on coolin yield a clean oil substantially free from ree carbon. Gases subjected to a less thorough cleaning may contain more or less free carbon. The free carbon content of the product of the process is controlled by regulating the amount of tar blended with oils condensed from the gases.

The proportion of oil condensed from the cleaned-gases and blended with the tar to produce the tarry oil product depends upon the temperature of the tar, the temperature of the gases, the amount of each, the percent of oil vapor in the gases, etc. Where the temperature and amount of tar are not suiiicient to separate the desired amount of clean oils from the gases, additional means may be provided for further cooling the gases during the operation of bringing the tar and gases into contact. The amount of oils separated from the gases may thus be increased. To accomplish this a small amount of water or ammonia liquor maybe mixed with the tar employed. Another way of accomplishing the result is to recirculate a portion of the tarry oil product,bringing it into Contact with the gases. This may advantageously be done by blending a portion of the tarry oil product with the tar before it is brought into contact with the gases. The temperature of both the tar and the tarry oil may advantageously be regulated before they are brought into contact with the gases. By cooling the tar and tarry oil a larger proportion of clean oils will be recovered from the gases in the tarry oil.

The invention will be described in the accompanying drawings more particularly as applied to the operation of a coke oven battery to produce creosoting composition, but it is intended and is to be understood that the invention is not limited thereto.

Fig. 1 shows more or less diagrammatically means for scrubbing ordinary gases to remove entrained impurities and then other means for cooling the gases with tar, such as a tarry oil to produce a blended tarry oil product of regulated composition.

Figs. 2 and 3 show details of Fig.` 1 in elevation and cross section;

Fig. 4 shows more or less diagrammatically means for cleaning ordinary gases in an electrical precipitator and a scrubber and ,cooler for producing a desired tarry oil product by washing a portion of the cleaned gases with tarry oil;

. Fig. 5 shows more or less diagrammatically a Amodification of apparatus for carrying `yout the process of my invention; and

Figs. 6 and 7 show a plan view and elevation, partly in section, of means for distilling tar and producing clean enriched gases from which a heavy condensate is condensed with means for washing and cooling the resulting gases with tarry oil to produce a desired tarry oil product.

In the drawings 5 indicates a coke oven battery equipped in the usual way with uptake pipes 6 which lead from the coke ovens to a collector main 7 from which the gases pass through thecenter-box 8 t0 the crossover main 9. A scrubber 10 is located in the cross-over main and preferably closely adjacent to the collector main. This scrubber is connected by a main 11 with a combined scrubber and condenser 12 in which the hot clean gases from the scrubber 10 are brought into direct contact with tar or tarry oil to produce creosoting composition or other desired tarry oil product.

The scrubber 10 represents means :forv

bringing a scrubbing medium, which may be tar or pitch into intimate contact with the hot gases. The scrubber comprises a chamber containing a roll 13 which is adapted to be rotated at high speed, in the neighborhood of 900-1200 R. P. M. by the motor 14. This roll 13 dips to a slight extent into the scrubbing medium which collects in the bottom ofthe scrubber and which may be admitted' to the scrubbing device through the pipe 15. The gases enter the scrubber from the main 9 and are brought into intimate contact with the intense spray of scrubbing medium thrown from the roll 13 and the cleaned gases pass out of the scrubbing device through the settling chamber 16 in which entrained particles olf'the scrubbing medium in the collector main is advantageously so.

regulated that the gases leave the main at a higher temperature than ordinary, so that a high percentage of the oils, including oils,

of high boiling range, pass over with the gases to, and to a large extent through, the gas cleaning device.

The scrubbing medium may advantageously be a pitch of the same co-mposition as that carried by the gases as they leave the collect-or main. This pitch on being sprayed into the gases removes entrained pitch particles and the pitch is preferably maintained at substantially the temperature of the gases so that pitch particles are removed from the gases without substantial .change in the composition of the gases, i. e., without increase or decrease in the'oil vapor contentof the gases. The pitch removed from the gases is withdrawn from the scrubber 10 through the trap 19 and the levelling arm 2Q. This pitch,

which is collected in the receiver 21, may be i tion of the material collected in 21 may be recirculated through the scrubber through the line l5 where this is considered desirable.

The condenser and washer 12 may be of the same structure as the scrubber 10 except that as here shown it may be desirable to allow the washing medium to flow through the washer in a direction generally counter-current to the flow ofthe gases, i. e., the washing medium may advantageously be admitted to the washing device through sprays in the tower corresponding to the tower 16 on the scrubber 10 and the product produced in the washer and condenser 12 may be withdrawn from the washing device at a point adjacent to where the main 11 enters the washing device l2. It is to be understood that either concurrent or counter-current flow of the washing medium in 12 and also of the scrubbing medium in 10 may be employed.

Fig. 1 provides for using as the washing medium in 12, tar from the collector main, i. e., the tar Withdrawn from the decanter 22 into the tar receiver 23, or tar from an outside source, such as the tank 24, may be used. The tar is admitted to the washing device 12 preferably continuously, and the flow is so adjusted that the proper proportion of this tar and clean oils separated from the gases on cooling, are blended together to produce the tarry oil desired which may be suitable for direct use as a creosoting composition,

' or in the preparation of creosoting composition. This product is collected in the sterage tank 25.

The temperature of the tar may be regulated in the cooler 26 in which it may be brought into indirect contact with cold water or brine, etc. Where desirable, as in the preparation of creosoting composition, the temperature of the tar and quantity of the tar admitted to the washing device are preferably so regulated that low boiling undesirable constituents will be volatilized from the tar by the gases, and low boiling undesirable constituents contained in the gases will pass from the washing device in vapor form and can be recovered in the condenser 27 together with vapors distilled from the tar used for washing the gases and together they will be withdrawn into the tank 28. The oils Collected in tank 28 comprise a low boiling clean oil fraction which may be utilized as for example for the preparation of tar acids byv extracting tar acids from the same with caustic alkalies. The condenser 27 may Ibe of either the direct or indirect type, but is here shown as of the indirect type. The eX- hauster 29 is employed for drawing the gases through the system and means for the recovery of ammonia and light oils may be located beyond this eXhauster.

In order to increase the extent to which the gases are cooled during the blending operation and hence increase the amount of oils condensed from the gases and blended with the tar, a portion of the tarry oil Jrom^25 may be recirculated through the line 25', and preferably through the cooler 26, and sprayed into the gases passing through 12. By regulating the amount recirculated, and the amount of cooling, the nature of the blend produced can be controlled.

Figs. 4 and 5 show an alternative arrangement employing an electrical precipitator for cleaning the gases and means for washing only a portion of the clean gases to produce creosoting composition or other tarry oil, with the'production of clean oils from the balance of the gases and from the gases and vapors leaving the washing device.

In Fig. 4 the gases from the collector main 40, which may be of the usual type, and connected with the ovens of the battery and with the cross-over main 41, in the usual manner, are passed into the electrical precipitator 42 and cleaned at a temperature approaching that at which they leave the collector main 40, which is preferably maintained at a temperature higher than usual, by limited cooling of the gases in the collector main. This precipitator may be of the usual Cottrell type in which the gases pass through tubes which serve as collecting electrodes and in which discharge electrodes are suspended through the collecting electrodes. The precipitator is connected with a source of uni-directional current of high potential and the gases in passing through the precipitator are subjected to a silent electrical discharge which causes entrained particles to be separated from the gases and to collect on the walls of the tubes. The precipitated material runs down the tubes, is collected in the bottom chamber of the precipitator and is withdrawn into a tank 43 and comprises a pitch of higher or lower melting point, which may be employed for any suitable purpose. The melting point of the pitch will be dependent upon the temperature at which the gases are cleaned and this may be regulated to a greater or less eX- tent by regulating'the cooling to which the gases' are subjected in the collector main. The temperature should be so regulated that the gases are not sufficiently hot to cause coking of pitch upon the electrodes in the precipitator, or the precipitator should bel supplied with means for washing the electrodes withpitch, etc. to prevent such coking.

The clean gases are divided into two portions which pass through the mains 44 and 45. The gases passing through the main 45 enter near the bottom of scrubber 46 which may be of the ordinary tower type and may contain baffie means such as Raschig rings. The gases is passing up through this scrubbing tower are washed with tarry oils passing down through the tower. These tarry 4oils may be the tar usually obtained from the coolers in the ordinary coke oven system. The tarry oils at regulated temperature are conveyed to the scrubber through the line 46a and are preferably sprayed into the gases within the tower, and are supplied in suicient quantity to produce a tarry oil of desired composition in the tank 47. A portion of the tarry oil from 47 may be recirculated through the scrubber 46 to regulate the cooling of the gases in this scrubber, and thus the amount of clean oils separated from the gases may be controlled. This portion of the tarry oil may be recirculated through the line 47a. It may be passed thru a cooler or not as required.

The temperature of the tarry oil and the temperature of the gases are so regulated that lighter constituents of the tarry oil sprayed into the gases in the scrubber, which are not desired in the nal tarry oil product, are distilled on being brought into direct contact with the gases, and low boiling constituentsIv present in the gases entering the scrubber through the main 45 remain uncondensed and pass through the scrubber in vapor form.

rlhese gases containing combined vapors of lower boiling oils leave the scrubber through the main 48 and enter the light oil condenser 49 where they are combined with gases and vapors from the condenser 50 which enter the condenser 49 through the main 51. In the condenser 50, which may be of the direct or indirect type, and is here shown as an indirect condenser, high boiling clean oils are condensed and collected in the tank 52. Likewise a total oil containing both high and low boiling oils may be condensed and recovered in 50. The condenser 49 may be of the direct or indirect type, andis here shown as an indirect condenser. Light oils condensed in this condenser are collected in the light oil tank 53. An eXhauster 54 is shown and means for recovering ammonia and light oils may` be located beyond the exhauster.

The arrangement in Fig. 5 shows a collector main 40', cross-over main 41, electrical precipitator 42 and pitch receiver 43 similar lto those shown in Fig. 4. The gases from the precipitator divide and pass through the mains 45 and 55. The main 45 leads to the scrubber 4 6', which may be of the same type as the scrubber 46 of Fig. 4. The gases are washed in the scrubber with a tarry oil such as the tarry oil produced in the condensers of the ordinary coke oven system and by proper regulation of the temperature of the gases entering the scrubber 46 by regulating the cooling to which the gases'are subjected in the collector main 40 and properly regulating the proportion of tarry oils admitted to the scrubber 46', and where necessary by cooling and recirculating a portion of the product from the tank 47 a tarry oil of desired composition can be produced, e. g.,

a tarry oil suitable for use directly as a creosoting composition.v

The gases from the scrubber pass through the main 56 and combine with the gases from the main 55 in the condenser 57 where a relatively heavy oil is separated from the gases and collected in the heavy oil tank 58. From there the gases pass to the condenser59 where lighter oils are condensed which'collect in the lighter oilreceiver 60. These are clean oils. The condensers 57 and 59 may be ofthe director indirect type and are here shown as indirect condensers. The character of the oils received from the various coolers or condenser-s may readily be controlled by regulation of the degree to which the gases are cooled. An exhauster is shown at 61.

Other cleaning means, such as scrubbers may be used instead of the precipitators shown in Figs. 4 and 5. Conversely a precipitator may be employed instead of the scrubber 13 of Fig. 1.

In Figs. 6 and 7 modied apparatus is shown in which the gases leaving the ovens are cleaned with tar and the tar is distilled to a high melting point pitch. The coke oven battery is represented at and is provided.y

in the usual way with uptake pipes 7l, a collector main 72 and cross-over main 73 which are here shownmore or less diagrammatically.

At the rear of the coke oven block a hot gas header 74 is shown, which is connected with selected coke ovens through uptake pipes 75. By the proper manipulation of valves in the uptake pipes 71 and in the uptake pipes 75, the hot gases from the selected ovens may be delivered either to the usual collector main 72 or to the hot gas header 74. The hot gases pass through the header 74 into the still 76. The still comprises a vchamber containing a roll 77 connected with a motor 78 which is adapted to rotate the roll at high speed, for example 9004200 R. P. M. The gases pass from the still through the tower 79 to means for'the separation of distillate oils from the gases.

The tar to be distilled in 76 is fed into the tower 79 through the spray 80 and passes over baille means 81 in intimate contact with the hot gases leaving the still. The gases, after passing the sprays 80, pass through the baffle means 82. The baile means, the diameter of the tower, and the spray, etc., are adjusted to remove entrained particles of tar spray carrier-by the gases from the still and to allow them to settle out of the gases. The spraying of the tar into the tower before it enters the still also serves to preheat the tar and partially distill it by bringing it into intimate contact with the gases and vapors escaping from the still. The tar sprayed into the settling tower collects in the bottom of the tower as soft pitch or partially distilled tar and the latter is fed through the line 83 into the end of the still adjacent to the opening from the hot gas header. The partly distilled tar flows through the still in the same direction as the gases. The tar is sprayed into the hot gases by the rapidly rotating roll and removes entrained impurities from the gases, and the tar itself is distilled to a pitch which may be a pitch of a 10 high melting point, for example, pitch with a melting point of 350 F., or oven 400 F., although pitches of lower melting point are likewise readily made. The pitch is withdrawn from the still through the trap 84 and the levelling arm 85 and on coming into contact with the cold water sprayed from the nozzle 86, the pitch is granulated and collects in the pitch storage tank 87. Pitches of low or medium melting point may be collected and held in liquid condition where desired.

The position of the spray roll in the still, and the speed of rotation of the roll are adjusted to give an intense spray of tar in the gases. This exposes a large surface of the tar to the gases which makes for efficient distillation of the tar by the gases. A sufiiciently intense spray of tar in the gases will scrub the' gases so that the gases and vapors leaving the tower 79 will be substantially free from entrained impurities, and on cooling clean oils will separate from the gases.

The still, the hot gas header, the uptake pipes 75, the tower 79 and the connecting mains are advantageously heavily insulated to prevent cooling of the gases through heat radiation.

Where'the tar is distilled to a very high melting point pitch the highest boiling con- 40 stituents distilled from the tar are advantageously removed from the gases before they are cooled with tar to produce the tarry oil product. This may be desirable in the preparation of special creosoting composition, for example. For this purpose the hot enriched gases passing from the settling tower are passed up through the hot condenser 88 in which high boiling constituents, which may comprise constituents which are solid or semi-solid at ordinary temperature, are condensed from the gases. The high boiling constituents removed in the hot condenser 88 collect in the storage tank 89. The degree of cooling in condenser 88 is regulated to avoid excess cooling with attendant condensation of lower boiling oils.

The resulting hot clean and partially cooled gases enter the washing tower 90 where they are scrubbed with tar. This may be a scrubber of the usual type, such as the type referred to by the reference numerals '46 and 46 in Figs. 4 and 5. This scrubber may contain bale means such as Raschig rings, or the baiies 91 here shown. Tarry oil, such as the tarry oil from the condensers of the usual coke oven plant, may be the tar used for cooling the gases and blending with the clean oils carried by the gases. It is sprayed into the gases rising through this scrubber or washing tower 90 through the 70 nozzle 93 which is supplied by the line 92. The tarry oil passes down through the tower counter-current to the iow of hot clean gases up through the tower. The tarry oil condenses clean oils from these hot gases. Where it is desirable to remove low boiling constituents of the tarry oil in order to produce a tarry oil relatively free from lower boiling constituents present in the scrubbing medium, the rate and temperature at which the scrubbing medium is fed to the gases is advantageously so regulated that undesirable low boiling ingredients are volatilized by the hot gases. The composite tarry oil which collects in the bottom of this washer 90, which comprises clean oils separated from the gases and constituents of the tarry oil sprayed into the gases, is drawn oi into the tarry oil receiver 94. A portion of this tarry oil may be recirculated through the scrubber through the line 94. By proper regulation of the temperature of the hot clean gases entering the washer, which may be obtained by adjusting the cooling to which the gases are subjected in the condenser 88, and by regu- 95 lating the temperature and amount of the tarry oil entering the tower from the line 92 and, where necessary, by cooling a portion of the tarry oil obtained in 94 and recirculating it through the tower, a product will be obtained in 94 which may be used directly as a creosoting composition, or used in the preparation of creosoting composition. A cooler 95 is shown for regulating the temperature of the scrubbing and condensing medium.

The low boiling constituents of the tarry oil admitted at 93, which are volatilized-in the washing chamber, and low boiling vapors carried by the gases entering the washing chamber which are not removed from the gases in 90, will leave this chamber through the main 95 and on cooling in the condenser 96 a clean light oil fraction will be produced which may be drawn ofl' into the clean oil 115 receiver 97. An exhauster is shown at 98. The condenser 96 which may be of the direct or indirect type is here shown as a direct condenser.

The free carbon content of tarry oils produced by washing clean coal distillation gases by tar may be controlled by regulating the amount of tar employed in proportion to the clean oils separated from the gases. The amount of clean oils which separate from the gases depends upon the temperature and amount of tar employed for washing the cleaned gas and upon the temperature of the cleaned gases. By recirculating a portion of the tarry oil produced through the washing \30 tower, the amount of oils present in the tarry oil product can be increased. The boiling range of the tarry oil produced by washing the gases may also be regulated by controlling the temperature of the gases and the temperature and amount of the Washing medium. By proper regulation of the variables a tarry oil of -desired propertiets may be produced directly by the processes herein described,

e. g., a tarry oil suitable for creosoting composition or a tarry oil from which a, creosoting composition of desired properties may be produced without the addition of a large amount of distillate thereto.

The process as indicated by Figs. l to 4,

inclusive, involves the treatment of all the gas from the collector mains. This is not essential; a regulated amount of gas may be withdrawn from the collector mains through a separate scrubbing and condensing system. In that way limited amounts of the desired oil may be produced without the use of equipment of large capacity required if all gas is treated. The final cold gas from such a system can be blended with the normal cold gas from the regular coolers. Likewise, if desired, separate small collector mains with separate scrubbing and cooling systems can be installed to receive from the ovens or retorts such alimited quantity of gas as may be desired.

l claim: l. A method of producing tarry oil which comprises, cleaning fresh hot coal distillation gases so as to remove entrained pitch constituents at a temperature at which a substant-ial proportion of condensable oils is retained in the gases in vapor form, and then bringing tar into contact with the clean hot gases so as to condense clean oils therefrom whereby the clean oils blend with the tar and form tarry oil.

2. A method of producing tarry oil which comprises, spraying tar into fresh hot coal distillation gases in the form of a fine intense spray whereby the tar is distilled and the gases are enriched in oil vapors and entrained impurities are scrubbed out of the gases, then bringing tar into the resulting scrubbed hot enriched gases whereby the gases are cooled and clean oil are condensed therefrom and blend with the tar and produce tarry oils.

In testimony whereof I afHX my signature.

STUART PARMELEE MILLER. 

